Explosive



United States Patent EXPLOSIVE Thomas Gaynor Blake, Florissant, Mo.,assignor to Olin Mathieson Chemical Corporation, East Alton, 111., acorporation of Virginia No Drawing. Filed Jan. 17, 1955, Ser. No.482,375

9 Claims. (Cl. 52-6) This invention relates generally to explosives andmore particularly to a novel defiagrating type of explosive composition.

Secondary explosives such as trinitrotoluene, tetryl andcyclotrimethylenetrinitramine and mixtures of such with ammonium nitrateand other materials have been ordinarily utilized heretofore as theexplosive charge in pro jectiles adapted for destroying aircraft,military tanks and similar devices. Such projectiles must be capable ofsuccessful functioning at the low pressures and temperatures of highaltitudes and at the same time must be resistant to guns whosetemperatures are elevated as a result of successive multiple firing.Further, to have any utility they must be capable upon reaching theirobjective of dealing a destructive blow and any improvement in thedestructive power of the explosive charge used in such projectiles isadvantageous. While many explosives and explosive compositions havegreat destructive power, not all will function satisfactorily under sucha variety of conditions of temperature and pressure and most inparticular do not have a satisfactory cook-off time. The period of timethat an explosive can be subjected to the elevated temperatures of a gunwhich has become heated by firing several cartridges in rapid successionis commonly known as the cook-off time and the most desirable explosivesfor use in projectiles to be fired from rapid fire guns are those havingmaximum cook-off times.

It is, therefore, an object of this invention to provide a novelexplosive composition particularly well suited for use in projectiles tobe fired from guns adapted to fire cartridges in rapid succession.Another object of this invention is to provide an explosive compositionhaving improved demolition properties or high blast effect and havingsufiicient heat stability to enable its use in explosive projectiles tobe fired from rapid fire guns. A more specific object of this inventionis to provide an explosive composition adapted for use in projectiles,bombs or the like having improved demolition characteristics or blasteffect over conventional explosive compounds such ascyclotrimethylenetrinitramine, trinitrotoluene, tetryl and the like andhaving the additional property of improved heat stability over suchexplosives.

The foregoing objects as well as others are accomplished in accordancewith this invention by providing a composition containing a major amountof a metal having a high heat of oxidation, an oxidizer for the metalcoated with trinitrotoluene or other suitable sensitizing explosive, anda minor amount of cyclotetramethylenetetranitramine. More specifically,the invention contemplates an explosive composition containing fromabout 30 to about 70 percent of powdered aluminum, magnesium, zinc,zirconium, titanium, boron, alloys thereof, or mixtures thereof, fromabout 18 to about 35 percent of an oxidizer for the metal and from about2 to about 4 percent trinitrotoluene intimately associated with theoxidizer and from about 6 to about 30 percentcyclotetramethylenetetranitramine. The oxidizer should be either aperhalate of ammonium, a perhalate of an alkali metal, or a nitrate ofone of the alkali metals or alkaline earth metals.

It is usually advantageous to mold pellets from the explosivecomposition and to thereafter use the pellets as the charge in explosiveprojectiles. This composition can be conveniently pelleted by firstmixing it with about 2 parts calcium stearate and about one partgraphite per 100 parts of the explosive composition.

The following specific examples have been found particularlyadvantageous for loading explosive projectiles used in conventional 20millimeter and 40 millimeter cartridges:

Example 1' Parts Aluminum About 54 Ammonium perchlorate About 36Trinitrotoluene About 4 Cyclotetramethylenetetranitramine About 5.8Parafiin wax About 0.2

Example ll Aluminum About 50 Potassium nitrate About 18 TrinitrotolueneAbout 2 Cyclotetramethylenetetranitramine About 29 Parafiin wax About 1Example III Aluminum About 50 Barium nitrate About 18 TrinitrotolueneAbout 2 Cyclotetramethylenetetranitramine About 29 Parafiin wax About 1Example IV Magnesium About 54 Ammonium perchlorate About 36Trinitrotoluene About 4 Cyclotetramethylenetetranitramine About 5.8Paraffin wax About 0.2

In each of the foregoing examples the various parts of the ingredientsare expressed as parts by weight. In each instance, in order to insurethat the trinitrotoluene is closely associated with the oxidizing agent,the particles of the oxidizer are coated with trinitrotoluene. Thiscoating can be achieved by melting the trinitrotoluene and pouring itover the crystals of the ammonium perchlorate or other oxidizer whilethe oxidizer is at a temperature of from about 92 C. to about 95 C. Theparticles of the oxidizer should be stirred until the trinitrotoluene isdistributed substantially uniformly over the crystals. An alternatemethod for coating the particles of the oxidizer with trinitrotolueneinvolves dissolving the trinitrotoluene in acetone or other low boilingsolvent for the trinitrotoluene and non-solvent for the oxidizer,pouring the solution over the crystals of the oxidizer and agitatinguntil a uniform dispersion is obtained and thereafter removing theacetone or other solvent by evaporation.

In forming the explosive composition the trinitrotoluene coatedoxidizer, the powdered metal and the cyclovided by this invention ismuch more effective for destroying hollow structures such as aircraftwings than a similar weight of any of the conventional explosives suchas cyclotrimethylenetrinitramine, trinitrotoluene or tetryl. Forexample, in tests in which projectiles containing explosive charges arefired into hollow aluminum panels, simulating the Wing of an airplane,the explosive composition of this invention is over ten times asdestructive as a projectile containing an equal weight of tetryl.

The composition provided by this invention is relatively heat stable andprojectiles containing the same can be safely left in the chamber of agun which has become heated by the firing of several rounds ofammunition in rapid succession for a longer period of time than canprojectiles containing tetryl, cyclotrimethylenetrinitramine, andsimilar explosives. This characteristic of improved cook-off time is adistinct advantage in projectiles utilized by aircraft because the gunsused are capable of firing cartridges in rapid succession and becomeheated to well above 280 F. As an example of the improved heat stabilityof the explosive composition provided by this invention it has beenfound that the composition having cyclotetramethylenetetranitramine ismuch more heat stable than a similar composition in whichcyclotrimethylenetrinitramine has been substituted for thecyclotetramethylenetetranitramine. In one type of test designed to bringout the difference in heat sta bility of the various explosive compoundsabout 0.3 gram of an explosive is placed in a small glass capsule andthe open end is sealed to provide a gas-tight capsule. The capsule isthen immersed in a molten Woods metal bath at a known temperature andthe length of time required for the explosive to detonate is accuratelymeasured. When the explosive composition of this invention was comparedwith explosive compositions similar in all respects thereto except thatcyclotrimethylenetrinitramine was substituted forcyclotetramethylenetetranitramine it was found that the compositioncontaining the cyclotetramethylenetetranitramine could be immersed inthe molten metal having a temperature of 250 C. for 46 minutes beforethe mixture detonated. The composition containingcyclotrimethylenetrinitramine exploded after only 12 minutes immersiontime.

It is believed that the unusually good demolition characteristics of theexplosive provided by this invention are due to the fact that the gasesdeveloped by the explosion of the relatively small amount of explosivecompound, namely cyclotetramethylenetetranitramine, are rapidly andgreatly increased in volume by the intense heat developed by the burningof the metal powder. In a sense the explosion may be a two-step processin which the explosive compound, cyclotetramethylenetetranitramine,first explodes and ignites the metal which because of the presence ofthe efficient oxidizing agent burns very rapidly and developes anintense heat which greatly expands the volume of gas developed by theexplosion of the cyclotetramethylenetetranitramine. For best results,the granulation of the metal must be such that it burns very rapidly soit is preferred that the granulation of the metal be such thatsubstantially 100% thereof will pass through a Standard U.S. 200 meshscreen. In other words, the maximum particle size should be about 74microns. Also for best results the granulation of the oxidizing agentshould be such that 100% thereof will pass through a 100 mesh screen andnot more than about 50% thereof will pass through a 325 mesh screen. Inother words, 100% of the particles of the oxidizer should have agranulation of not more than about 150 microns and 50% thereof should beless than 44 microns. The explosive composition provided by thisinvention should have a granulation such that all particles will passthrough a U.S. Standard No. 40 sieve and not more than about will passthrough a U.S. Standard No. 60 sieve. In order to waterproof thecyclotetramethyl- '4 enetetranitramine the particles thereof arepreferably coated with parafiin wax in the amount of about 0.2% byweight of the total composition.

Several specific examples have been given in the foregoing for thepurpose of illustration but it is to be understood that each particularcomposition can be varied within the limits specified therein for eachingredient and that each of the metals contemplated for this inventioncan be utilized in the particular embodiments presented in detail. It isalso to be understood that other modifications can be made in theinvention by those skilled in the art without departing from the spiritand scope thereof except as it is limited by the appended claims.

I claim:

1. As a new composition of matter, an explosive composition consistingessentially of from about 30 percent to about 70 percent of powderedmetal selected from the group consisting of aluminum, magnesium, zinc,titanium, zirconium, boron, alloys thereof and mixtures thereof, about18 percent to about 36 percent of an oxidizer selected from the groupconsisting of a perhalate of ammonium, a perhalate of an alkali metal, anitrate of an alkali metal, and a nitrate of an' alkline earth metal,from about 2 percent to about 4 percent of trinitrotoluene in the formof a coating on the particles of the oxidizer, and about 6 percent toabout 30 percent cyclotetramethylenetetranitramine.

2. The composition of claim 1 wherein said metal is aluminum.

3. The composition of claim 1 wherein the metal is aluminum and theoxidizer is ammonium perchlorate.

4. The composition of claim 1 wherein the granulation of the metal isnot more than about 200 microns and the particle size of the oxidizer issuch that thereof is no greater than about 74 microns and at least about5% thereof has a granulation of not more than about 44 microns.

5. An explosive composition consisting essentially of from about 30percent to about 70 percent of aluminum, about 18 percent to about 36percent of barium nitrate coated with about 2 percent trinitrotoluene,and about 6 percent to about 30 percent ofcyclotetramethylenetetranitramine.

6. An explosive composition, adapted for use in pro jectiles designed todestroy hollow targets, consisting essentially of from about 30 percentto about 70 percent of a powdered metal selected from the groupconsisting of aluminum, magnesium, zinc, titanium, zirconium, boron,alloys thereof, and mixtures thereof, from about 18 percent to about 35percent of an oxidizer for the metal coated with trinitrotoluene andfrom about 6 percent to about 30 percent ofcyclotetramethylenetetranitramine.

7. As a new composition of matter, an explosive composition consistingessentially of from about 30 percent to about 70 percent of a powderedmetal selected from the group consisting of aluminum, magnesium, zinc,titanium, zirconium, boron, alloys thereof, and mixtures thereof, about18 percent to about 36 percent of an oxidizer for the metal selectedfrom the group consisting of a perhalate of ammonia, a perhalate of analkali metal, a nitrate of an alkali metal, and a nitrate of an alkalineearth metal coated with from about 2 percent to about 4 percent oftrinitrotoluene, and about 6 percent to about 30 percent ofcyclotetramethylenetetranitramine coated with paraffin wax.

8. As a new composition of matter, an explosive composition consistingessentially of from about 30 percent to about 70 percent of a powderedmetal selected from the group consisting of aluminum, magnesium, zinc,titanium, zirconium, boron, alloys thereof, and mixtures thereof. about18 percent to about 36 percent of an oxidizer for the metal selectedfrom the group of a perhalate of ammonia, a perhalate of an alkalimetal, a nitrate of an alkali metal, and a nitrate of an alkaline earthmetal, from about 2 percent to about 4 percent of trinitrotoluene as acoating on the oxidizer, and from about 6 percent to about 30 percent ofcyclotetramethylenetetranitramine.

9. The composition of claim 7 wherein the metal is aluminum.

6 References Cited in the file of this patent UNITED STATES PATENTSWyler Nov. 5, 1946 FOREIGN PATENTS Italy Mar. 27, 1943

1. AS A NEW COMPOSITION OF MATTER, AN EXPLOSIVE COMPOSITION CONSISTINGESSENTIALLY OF FROM ABOUT 30 PERCENT TO ABOUT 70 PERCENT OF POWDEREDMETAL SELECTED FROM THE GROUP CONSISTING OF ALUMINUM, MAGNESIUM, ZINC,TITANIUM, ZIRCONIUM, BORON, ALLOYS THEREOF AND MIXTURES THEREOF, ABOUT18 PERCENT TO ABOUT 36 PERCENT OF AN OXIDIZER SELECTED FROM THE GROUPCONSISTING OF A PERHALATE OF AMMONIUM, A PERHALATE OF AN ALKALI METAL, ANITRATE OF AN ALKALI METAL, AND A NITRATE OF AN ALKLINE EARTH METAL,FROM ABOUT 2 PERCENT TO ABOUT 4 PERCENT OF TRINITROTOLUENE IN THE FORMOF A COATING ON THE PARTICLES OF THE OXIDIZER, AND ABOUT 6 PERCENT TOABOUT 30 PERCENT CYCLOTETRAMETHYLENETETRANITRAMINE.